Outdoor navigation using Global Navigation Systems (“GNSS”) is largely known. The technology is widespread and regularly used. Many indoor navigation and positioning systems rely on having accurate positioning information for indoor infrastructure elements, such as wireless responders. These systems may rely on the measurement of a transmission time to determine an approximate distance, which is then compared with known positioning information to determine the location of a client device. For these systems, the responders must be very accurately time-synchronized. Accordingly, there is a need for a way to accurately time-synchronize, particularly over a large indoor positioning system implementation.
Furthermore, where accurate positioning information is not available, or where it is not relied upon in a positioning system installation, it may not be possible to track a client device's absolute position. Thus, there is a need to track the relative position of a client device, as it relates to a network of responders. Moreover, even though modern standards, such as Fine Time Measurements (“FTM”), allow for very accurate measurements of transmission time between a client device and a responder, not all devices are capable of FTM, nor is FTM desirable in all situations. Accordingly, there is a need to create a positioning system that can be used without FTM, such as on legacy devices.